The Start Device on the compressor clicks and turns on the compressor, Compressor doesn't keep running,(and fan motors seem to slow down), Then clicks again, and compressor tries to start again, and shuts down. Sometimes this goes on for 3 to 6 cycles. I think its the capacitor. The relay checks out and the compressor winding resistance is right in the middle as per the schematic on the fridge. There are several start device units listed whirlpool and universal. I would like to know so I can order, which is the most compatible... Your pn AP3873993 looks very close and or any of the 2 universals

I got from the order desk (but state no longer cross ref available)
Relay: 548834, or alternate 548836:
Capacitor 851846 ;
and overload 546572

Please let me know thanks